How do I make a curve at a specific number of degrees per unit of length?

I am trying to show a curved track that curves no more than 2 degrees in 10’ but even using the protractor, I can’t seem to “mark” that guideline so I can bulge the arc there midway (well, I guess midway is really just 5’ then, but even that would be OK). The track is two-sided and will be “grabbed” on either side by geared mechanisms, bending along the length to make a long arc.
Unfortunately, my elevator model is too large to upload now, but here is the Arch where a slightly revised version of the elevator will travel along the sloping channels on the inner edges of the Arch. Note this is not a concentric half circle to the outer circle. That is on purpose.
Arch 8b.skp (451.3 KB)

As we discussed privately, you are misunderstanding the meaning of the radius of an arc. And since the radius is of the order of 750 feet, the amount of bulge in 10ft of arc with that radius is negligible for almost all practical Sketchup purposes.

We redrew the track in a straight section, which is close enough for your purposes. Sections could be joined rotated 2° in your model, if you need to show more than one segment of track.

OK, though there’ll be a bit more curvature at the top of the inner arc now that it is more elliptical than half-circle.
I copied my track segment and put a concrete pillar in between them to support the weight of the ~2-ton elevator (fully loaded). I actually don’t need the metal cage around it anymore since the track is all mounted on the concrete pillar (with steel inside). Now I can finally get to my first floor plan.

You inner arc is still part of a circle, not an ellipse. It’s just more than half a circle, which the outside is. So it has no more ‘curvature’ at the top than at the bottom.